# GG-11: Capital Deepening MPK Robustness

Testing whether Z₁→investment and Z₁→MPK findings are robust.

| Test | Z₁ | p-value | N | Sample |
|---|---|---|---|---|
| Baseline: Z₁→gross_investment_gdp | 32.6*** | 0.0013 | 6620 | Full |
| OECD: Z₁→gross_investment_gdp | 31.1 | 0.1165 | 1611 | OECD |
| Non-OECD: Z₁→gross_investment_gdp | 39.3*** | 0.0019 | 5009 | Non-OECD |
| Baseline: Z₁→gross_fixed_investment_gdp | 28.4*** | 0.0037 | 6431 | Full |
| OECD: Z₁→gross_fixed_investment_gdp | 45.3** | 0.0115 | 1611 | OECD |
| Non-OECD: Z₁→gross_fixed_investment_gdp | 31.4** | 0.0105 | 4820 | Non-OECD |